1. Field of the Invention
The present invention relates to an enhanced feature connector for an overlay board. More particularly, it relates to an enhanced feature connector for an overlay board which transmits and receives digital data from a video graphics array feature connector and analog data from a video graphics array connector by using a single connector.
2. Description of the Related Art
An earlier connection of a feature connector and an overlay board was usually constructed with a video graphics array board for outputting a video signal to an output unit having a graphics control large scale integration (LSI) unit including a video graphics array unit which is requisite for generation of a video signal transmitted to a video display through cables; a feature connector for transmitting and receiving a video graphics array digital video signal which is generally used to overlay other signals; an overlay board for overlaying another video signal on a current operating program; and an analog connector 120 for transmitting analog video red (R), green (G), and blue (B) data signals outputted from the video graphics array board.
The overlay board received digital pixel data from the video graphics array feature connector of the video graphics array board as an input and received an analog video red, green and blue data signal from the video graphics array monitor connector as an input.
Typically, such overlay boards receive both the digital pixel data and the red, green and blue data signal, and generate a signal mixed by an internal circuit, and outputs the mixed signal to a monitor.
The earlier designs for overlay boards often included a feature connector for transmitting and receiving a video graphics array digital video signal used for overlaying other signals; a connector for receiving analog red, green and blue data from a video graphics array board as an input; an overlay controller for receiving digital signals such as pixel data, pixel clock, horizontal synchronization, and vertical synchronization and converting the digital signals into analog red, green and blue data in order to overlay video signals by loading plural display windows; an analog multiplexer (MUD for sequentially selecting both an input signal of analog red, green and blue data of the overlay controller and an input signal of analog red, green and blue data of a video graphics array board, dividing the input signals, and selecting a signal corresponding to each input signal; and a connector for transmitting output data from the analog multiplexer to a monitor.
The earlier overlay board received video graphics array data from a video graphics array board, combined the video graphics array data with the conventional overlay board's signal and finally applied the combined data to drive a monitor.
There are two kinds of paths for receiving a signal from the video graphics array board: digital signals such as a pixel data, pixel clock, horizontal synchronization signal, and vertical synchronization signal from the video graphics array feature connector; and analog red, green and blue data from the video graphics array connector. The earlier overlay controller used the pixel data for a color display, and generates the analog red, green and blue data. The analog multiplexer received the analog red, green and blue data from the overlay controller and other analog red, green and blue data from the video graphics array connector. The analog red, green and blue data signal from the analog multiplexer were applied to a monitor drive through a monitor connector.
I have found that in the earlier arrangement however, connectors for analog red, green and blue data were placed on the back side of a computer, thereby causing an inconvenience when installing a computer system. The connectors for analog red, green and blue data are connected to the computer system by using additional cables, thereby causing the possibility of a loss. Furthermore, I have also noticed that there are many connectors with the same shape on the back side is of the computer, thereby leading to misinsertion.
A function of a display data channel (DDC) is to transmit and receive commands between a video graphics array board and a monitor. When an overlay board is inserted between a conventional video graphics array board and a monitor, and a signal necessary for a display data channel is changed, the display data channel may not be able to operate.
Exemplary efforts representation of contemporary practice with computer systems having overlay features include U.S. Pat. No. 5,546,518 to Blossom et al. entitled System And Method For Composing A Display Frame Of Multiple Layered Graphic Sprites, U.S. Pat. No. 5,254,984 to Wakeland entitled video graphics array Controller For Displaying Images Having Selective Components From Multiple Image Planes, U.S. Pat. No. 5,093,798 to Kita entitled Image Processing System, U.S. Pat. No. 4,954,970 to Walker et al. entitled Video Overlay Image Processing Apparatus, U.S. Pat. No. 4,942,391 to Kikuta entitled Picture Information Composite System, U.S. Pat. No. 4,878,181 to MacKenna et al. entitled Video Display Controller For Expanding Monochrome Data To Programmable foreground And Background Color Image Data, U.S. Pat. No. 4,855,831 to Miyamoto et al. entitled Video Signal Processing Apparatus, and U.S. Pat. No. 4,800,423 to Appiano et al. entitled Interface Module For Superimposing alphanumeric Characters Upon RGB Video Signals. It is may observation however that the art represented by these exemplars fail to appreciate either the difficulties caused by contemporary practice in the art, or the need for an improvement in the connectors for graphics controllers.